Affinity and kinetics of the interactions between an alphabeta T-cell receptor and its superantigen and class II-MHC/peptide ligands

• Published in: Molecular immunology Vol. 34; no. 6; pp. 493 - 503
• Main Authors: Khandekar, S S, Brauer, P P, Naylor, J W, Chang, H C, Kern, P, Newcomb, J R, Leclair, K P, Stump, H S, Bettencourt, B M, Kawasaki, E, Banerji, J, Profy, A T, Jones, B
• Format: Journal Article
• Language: English
• Published: England 01.04.1997
• Subjects: Animals; Baculoviridae; Biosensing Techniques; Cells, Cultured; Histocompatibility Antigens Class II - metabolism; Kinetics; Ligands; Lymphocyte Activation; Moths; Peptides - immunology; Peptides - metabolism; Protein Binding; Receptors, Antigen, T-Cell, alpha-beta - metabolism; Recombinant Fusion Proteins; Solubility; Spectrum Analysis; Superantigens - metabolism
• ISSN: 0161-5890

Immune activation is mediated by a specific interaction between the T-cell receptor (TCR) and an antigenic peptide bound to the major histocompatibility complex (MHC). T-cell activation can also be stimulated by superantigens which bind to germline-encoded variable domain sequences of certain TCR beta-chains. We have used a surface plasmon resonance biosensor to characterize the molecular interactions between a class II-restricted alphabeta TCR and its superantigen and MHC/peptide ligands. The extracellular domains of the murine D10 TCR (Valpha2, Vbeta8.2) were expressed in insect cells and secreted as a disulfide-linked heterodimer. In the absence of MHC class II, purified soluble D10 TCR bound to Staphylococcus aureus enterotoxin C2 with an association rate of 1.69+/-0.12 x 10(4)M(-1) sec(-1) and a dissociation rate of 1.9+/-0.47 x 10(-2) sec(-1), giving a dissociation constant of 1.1 microM. Binding of the TCR to S. aureus enterotoxin B was barely detectable and could not be measured accurately due to the rapid dissociation rate. Soluble D10 TCR also bound to a soluble murine MHC class II I-A(k) molecule containing a fused antigenic conalbumin peptide and complementary leucine zipper sequences to facilitate efficient chain pairing. The purified I A(k) chimera specifically stimulated proliferation of the D10 T-cell clone, and bound to immobilized soluble D10 TCR with an association rate of 1.07+/-0.19 x 10(4)M(-1)sec(-1) and a dissociation rate of 2.2+/-0.65 x 10(-2) sec(-1), giving a dissociation constant of 2.1 microM.